Download Energy Outline Notes - Darlington Middle School

Energy Parent Outline Notes
Energy Types:
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Energy can be in many different forms.
o Heat energy
 Heat energy is the transfer of thermal energy
 energy that is from the motion of the particles of a substance
 As heat energy is added to a substance, the temperature goes
up indicating that the particles are moving faster.
o The faster the particles move, the higher the
temperature.
 Material (wood, candle wax) that is burning, the Sun, and electricity
are sources of heat energy.
o Solar energy
 Solar energy is the energy from the Sun, which provides heat and
light energy for Earth.
 Solar cells can be used to convert solar energy to electrical energy.
 Green plants use solar energy during photosynthesis (6-2.7) to
produce sugar, which contains stored chemical energy.
 Most of the energy that we use on Earth originally came from the
Sun.
o Chemical energy
 Chemical energy is energy stored in particles of matter.
 Chemical energy can be released when these particles react to form
new substances.
 for example in batteries or sugar/food
o Electrical energy
 Electrical energy is the energy flowing in an electric circuit.
 Sources of electrical energy include:
 stored chemical energy in batteries
 solar energy in solar cells
 fuels
 hydroelectric energy in generators.
o Mechanical energy
 Mechanical energy is the energy due to the motion (kinetic) and
position (potential) of an object.
 When objects are set in motion or are in a position where they can be
set in motion, they have mechanical energy.
 Mechanical Potential energy: Potential energy is stored energy.
Mechanical potential energy is related to the position of an
object.
 A stretched rubber band has potential energy.
 Water behind a dam has potential energy because it can fall
down the dam.
Mechanical Kinetic energy: Kinetic energy is the energy an object has
due to its motion.
 Mechanical kinetic energy increases as an object moves faster.
A moving car has kinetic energy.
 If the car moves faster, it has more kinetic energy.
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Conservation of Energy:
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The Law of Conservation of Energy states that energy cannot be created or
destroyed.
o It may be transformed from one form into another, but the total amount of
energy never changes.
o Energy can be changed from one form to another as follows:
 Mechanical energy transformations
 The mechanical energy that an object has may be kinetic
energy or potential energy or some combination of the two.
 Energy transformations can occur between the two types of
mechanical energy.
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might include:
o When water is behind a dam, it has potential energy.
The potential energy of the water changes to kinetic
energy in the movement of the water as it flows over
the dam.
o When a rubber band is stretched, kinetic energy is
transformed into potential energy.
When a stretched rubber band is released its potential
energy is transformed into kinetic energy as the rubber
band moves.
o When a book is lifted to a shelf, kinetic energy is
transformed into potential energy.
o If the book falls off the shelf the potential energy is
transformed to kinetic energy.
 Mechanical energy transformations may involve other kinds of
energy. Examples might include:
o When the book in the example above hits the floor the
kinetic energy is transformed into other forms of
energy such as sound and heat.
o The water that runs over the dam might be used to
power an electric generator and thus the mechanical
energy from the water can be transformed into
electrical energy.
o The water was behind the dam because the energy
from the sun evaporated water and deposited it at a
higher elevation so that it could flow downhill thus solar
energy was transformed to potential mechanical energy.
Transformations may occur between any of the various types of energy but
the energy itself is always around in some form.
 It is never lost.
 Examples might include:
 Green plants transform the Sun’s energy into food which is a
form of stored chemical energy.
 Animals use chemical energy from food to move.
o The chemical energy in the food is transformed to
mechanical energy.
 Carbon-based fuels are all derived from of the bodies of
plants and/or animals.
o When carbon-based fuels (wood, natural gas, petroleum,
or coal) are burned, the chemical energy is transformed
to heat energy.
 The heat energy from fuels can be transformed to electrical
energy at a power plant.
 In an electric circuit the electrical energy can be transformed
into many different types of energy such as mechanical, sound,
light, and heat.
o
o
Electromagnets:
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Magnetism is the force of attraction or repulsion of magnetic materials.
o Surrounding a magnet is a magnetic field that applies a force without
actually touching an object.
o An electric current flowing through a wire wrapped around an iron core
forms a magnet.
o A coil of wire spinning around a magnet or a magnet spinning around a coil of
wire can form an electric current.
o Examples of how magnetism and electricity are interrelated can be
demonstrated by the following devices:
 Electromagnets
 An electromagnet is formed when a wire in an electric circuit
is wrapped around an iron core producing a magnetic field.
 The magnet that results loses its magnetism if the electric
current stops flowing.
 Generators
 A generator produces an electric current when a coil of wire
wrapped around an iron core is rotated near a magnet.
 Generators at power plants produce electric energy for our
homes.
 A generator contains coils of wire that are stationary, and
rotating magnets are rotated by turbines.
o Turbines are huge wheels that rotate when pushed by
water, wind, or steam.
 Mechanical energy is changed to electrical energy by a
generator.
o Smaller generators may be powered by gasoline.
 Simple electric motors
 An electric motor changes electrical energy to mechanical
energy.
 It contains an electromagnet that rotates between the poles
of a magnet.
 The coil of the electromagnet is connected to a battery or
other source of electric current.
 When an electric current flows through the wire in the
electromagnet, a magnetic field is produced in the coil.
 Like poles of the magnets repel and unlike poles of the
magnets attract.
 This causes the coil to rotate and thus changes electrical
energy to mechanical energy.

This rotating coil of wire can be attached to a shaft and a
blade in an electric fan.
Electrical Energy:
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Electrical energy can be transformed to light, sound, heat, and mechanical motion in
an electric circuit.
o An electric circuit contains a source, a conductor (wire) connected source,
and a device that uses and transforms the electrical energy.
o All these components must be connected in a complete, unbroken path in
order for energy transformations to occur.
o The electrical energy in circuits may come from many sources including:
 The electrical energy in a battery comes from stored chemical
energy.
 The electrical energy in a solar cell comes from light energy from the
sun.
 The electrical energy in outlets may come from chemical energy
(burning fuels) which powers a generator in a power plant.
Electrical energy can be transformed to other forms of energy in a circuit.
o Light
 Electrical energy can be transformed into light energy in an electric
circuit if a light bulb is added to the circuit.
 The transformation is chemical energy in a battery is transformed
into electrical energy in the circuit which is transformed into light
and heat energy in the light bulb.
o Sound
 Electrical energy can be transformed into sound energy in an electric
circuit if a bell, buzzer, radio, or TV is added to the circuit.
 The transformation is that chemical energy in a battery is
transformed into electrical energy in the circuit which is transformed
into sound energy.
o Heat
 Electrical energy can be transformed into heat energy in an electric
circuit if a toaster, stove, or heater is added to the circuit.
 Then the electrical energy in the circuit is transformed into heat
energy in the heater.
o Mechanical motion
 Electrical energy can be transformed into the energy of mechanical
motion if a fan or motor is added to the circuit.
Heat Transfers:
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Energy transfer as heat can occur in three ways:
o Conduction
 Conduction involves objects in direct contact.
 The transfer of energy as heat occurs between particles as they
collide within a substance or between two objects in contact.
 All materials do not conduct heat energy equally well.
 Poor conductors of heat are called insulators.
 The energy transfers from an area of higher temperature to an area
of lower temperature.
 For example, if a plastic spoon and a metal spoon are placed into a hot
liquid
 The handle of the metal spoon will get hot quicker than the
handle of the plastic spoon because the heat is conducted
through the metal spoon better than through the plastic
spoon.
o Convection
 Convection is the transfer of energy as heat by movement of the
heated substance itself, as currents in fluids (liquids and gases).
 Heat transfer occurs when particles with higher energy move from
warmer to cooler parts of the fluid.
 Uneven heating can result in convection, both in the air and in water.
o Radiation
 Radiation is the transfer of energy through space without particles
of matter colliding or moving to transfer the energy.
 This radiated energy warms an object when it is absorbed.
 Radiant heat energy moves from an area of higher temperature to an
area of cooler temperature.
Work:
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Energy is a property that enables something to do work.
o Work means to (1) apply a force to an object over a distance, and (2) the
object moves in response to the force.
If something has the ability to cause a change in motion, it is has energy.
Energy can cause work to be done, so when we see work done, we see evidence of
energy.
o For example:
 When a toy car at rest is pushed, work is done on the car if it moves.
This work (or movement) is evidence of energy.
 When a fan is connected to an electric circuit, it moves, so work was
done on the fan. This work (or movement) is evidence of energy.
 When an object is lifted, it moves, so work is done on the object.
This work (or movement) is evidence of energy.
A spring scale is used to measure force.
o Force (including weight) is measured in SI units called newtons (N).
Simple Machines:
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A simple machine is a device that helps reduce the amount of force required to do
work.
o Work is done when a force (effort force) is applied over a distance.
A simple machine allows the user to apply a smaller force over a larger distance to
move an object.
o Simple machines can also change the direction of the force applied.
o If the distance over which the effort force is exerted is increased, the
same amount of work can be done with a smaller effort force.
o This is the principle that simple machines use to reduce the amount of
effort force needed to do work.
The design of the simple machines can reduce the amount of force required to do
work:
o Lever
 A lever is a rigid bar or board that is free to move around a fixed
point called a fulcrum.
 The fulcrum may be placed at different locations along the
bar.
 A lever can be designed to reduce the amount of force required to
lift a weight in two ways:
 (1) By increasing the distance from the fulcrum to the point
where the effort force is applied
 (2) by decreasing the distance the weight is from the fulcrum.
o
o
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Pulley
 A pulley has a grooved wheel with a rope running along the groove.
 Pulleys can change the amount and/or the direction of the force
applied (effort force).
 By arranging the pulleys to add more distance, the effort force can
be reduced.
 Movable pulleys are used to reduce the effort force.
 A single fixed pulley changes only the direction of the force
 you pull down and the weight goes up
Inclined plane
 An inclined plane is a sloping surface, like a ramp, that reduces the
amount of force required to lift an object.
 An inclined plane can be designed to reduce the force needed to lift a
weight in two ways:
 (1) increase the length of the ramp
 (2) decrease the height of the ramp.
Simple machines are found in common tools and in complex (compound) machines.
o For example:
 Levers that have the fulcrum between where the effort force is
applied and the weight is located can be found in tools
 for example, scissors and crowbar.
 Levers that have the fulcrum on the end and the effort is applied in
the middle to lift a weight on the other end can be found in tools
 for example, tweezers or a broom.
 Levers that have the fulcrum on the end and the effort force are
applied on the other end to lift a weight in the middle can be found in
tools
 for example, a wheelbarrow, or a bottle opener.
Pulleys that are fixed, meaning that they are attached to a structure,
can be found on the top of a flag pole and on window blinds.
 Pulleys that are moveable, meaning that they are not attached to a
structure, can be found on construction cranes and as part of a block
and tackle system.
 Inclined planes with a sloping surface can be found as ramps on a
truck or wheelchair ramp and stairs.
 Inclined planes that are wedges are found as knife blades or nails.
 Inclined planes that are wound around a post or cylinder are called
screws.
 Screws can be found in bolts and jar lids.
 Wheel and axles consist of two circular objects: a central shaft,
called an axle, inserted through the middle of a wheel.
 Wheel and axles can be found as door knobs, steering wheels,
screwdrivers, gears, and bicycles wheels.
Complex machines
o Are also known as compound machines
o Consist of two or more simple machines.
o Examples may include:
 scissors consisting of two levers and two inclined planes (wedges)
 a fishing pole consisting of a lever, a wheel and axle and a pulley
 a bicycle consists of levers (handlebars and handbrakes), wheel and
axles (gears, wheels, and pedals), and a number of screws.
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